Backrest device

ABSTRACT

A backrest device comprises at least one backrest and at least one connecting unit having two springs, two jointing members and a connecting member. Each spring comprises a first end and a second end. Each jointing member is provided with at least one first engaging block for engaging with the first end of the spring. The connecting member is provided with at least one second engaging block for engaging with the second end of the spring and is fixed to a chair stably. When the user sits in the chair with his back leaning against the backrest, since the springs are flexible, which can enable the backrest to be freely adjusted and moved in response to the movement of the back of the user, producing a buffering effect and providing a comfortable support to the back of the user, so the user will feel comfortable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a backrest device, and more particularly to a backrest device which is assembled to a chair, so as to enable the backrest device to be freely adjusted and moved in response to the movement of the back of the user.

2. Description of the Prior Art

Usually, a conventional backrest for a chair is unmovable, when the user sits on the chair, the back of the user is abutted against the fixed backrest and repressed by the backrest, so the user will feel uncomfortable.

The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide a backrest device comprising at least one backrest and at least one connecting unit. On a rear surface of the backrest is provided with two positioning blocks. The connecting unit comprises two springs, two jointing members and a connecting member. Each spring comprises a first end and a second end arranged in a reverse direction to the first end. The jointing members are connected to the positioning blocks of the backrest, respectively. Each jointing member is provided with at least one first engaging block for engaging with the first end of the spring. The connecting member is provided with two connecting portions, and each connecting portion is provided with at least one second engaging block for engaging with the second end of the spring, and the connecting member is fixed to the chair stably.

When the user sits in the chair with his back leaning against the backrest, since the springs are flexible, which can enable the backrest to be freely adjusted and moved in response to the movement of the back of the user, producing a buffering effect and providing a comfortable support to the back of the user, so the user will feel comfortable.

The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiments in accordance with the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a backrest device being assembled to an office chair in accordance with a first embodiment of the present invention;

FIG. 2 is an exploded view of the backrest device in accordance with the first embodiment of the present invention;

FIG. 3 is an assembly cross sectional view of FIG. 2;

FIG. 4 is a plan view showing the movement of the backrest device in accordance with the first embodiment of the present invention;

FIG. 5 is an illustrative view showing the backrest device being assembled to a vehicle chair in accordance with a second embodiment of the present invention;

FIG. 6 is an exploded view of a variation of the backrest device in accordance with the first embodiment of the present invention; and

FIG. 7 is an assembly cross sectional view of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-3, a backrest device A in accordance with the present invention is assembled to a chair that can be an ordinary chair, a vehicle chair, an office chair or other chairs, and the backrest device A in accordance with a first embodiment of the present invention is assembled to the office chair 30.

The backrest device A comprises at least one backrest 10 and at least one connecting unit 20.

On a rear surface of the backrest 10 is provided with two positioning blocks 11, and each positioning block 11 is provided with a threaded sleeve 13 having an inner threaded portion 12.

The connecting unit 20 comprises two springs 21, two jointing members 22, a connecting member 23 and two mounting members 24.

Each spring 21 is flexible and comprises a first end 211 and a second end 212 arranged in a reverse direction to the first end 211.

Each jointing member 22 is defined with a through hole 221 through which a threaded member 222 is threaded in the inner threaded portion 12 of the threaded sleeve 13 of the backrest 10, so that the jointing members 22 are connected to the positioning blocks 11 of the backrest 10. Each jointing member 22 is further provided with at least one first engaging block 223 for engaging with the first end 211 of the spring 21, so that the jointing members 22 are fixed to the first ends 211 of the springs 21 stably.

The connecting member 23 is provided with two connecting portions 231 and is defined with a penetrating hole 232. Each connecting portion 231 is provided with at least one second engaging block 233 for engaging with the second end 212 of the spring 21, so that the connecting member 23 is fixed to the second ends 212 of the springs 21 stably.

Each mounting member 24 is made of flexible material and is defined with a hollow portion 241 for receiving the spring 21.

Referring to FIGS. 3 and 4, to assemble the backrest device A to the office chair 30 whose frame 31 is provided with a built-in nut 311, a bolt 234 is threaded through the penetrating hole 232 of the connecting member 23 into the built-in nut 311 of the frame 31 to fix the connecting member 23 to the frame 31, thus assembling the backrest device A to the office chair 30 stably. When the user sits in the office chair 30 with his back leaning against the backrest 10, since the springs 21 of the connecting unit 20 are flexible, which can enable the backrest 10 to be freely adjusted and moved in response to the movement of the back of the user, providing a comfortable support to the back of the user, so the user will feel comfortable. In addition, the mounting members 24 for receiving the springs 21 can protect the user from getting pinched by the springs 21.

Referring to FIG. 5, the backrest device A can also be assembled to a vehicle chair 40 for the user's back to rest against. The vehicle chair 40 comprises a headrest 41, a backrest 42 and a cushion 43. The connecting member 23 of the backrest device A is connected to a backboard 50 which is provided with a horizontal portion 51 of the backboard 50 to be inserted in a gap 44 formed between the backrest 42 and the cushion 43, then a band 52 that is disposed on the backboard 50 is suspended between the headrest 41 and the backrest 42, so that the backrest device A is assembled to the vehicle chair 40 stably. When the user sits in the vehicle chair 40 with his back leaning against the backrest 10, since the springs 21 of the connecting unit 20 are flexible, which can enable the backrest 10 to be freely adjusted and moved in response to the movement of the back of the user, providing a comfortable support to the back of the user, so the user will feel comfortable.

Referring to FIGS. 6 and 7, a variation of the backrest device A of the above-mentioned first embodiment of the present invention is shown, the backrest device A comprises at least one backrest 10 and at least one connecting unit 20. The structure of the backrest 10 is the same as that described in the first embodiment and will not be described in detail. In the above-mentioned first embodiment, each jointing member 22 utilizes one first engaging block 223 to engage with the first end 211 of the spring 21, and each connecting portion 231 of the connecting member 23 utilizes one second engaging block 233 to engage with the second end 212 of the spring 21.

In the variation shown in FIGS. 6 and 7, each jointing member 22 utilizes two first engaging blocks 223 to engage with the first end 211 of the spring 21, and each connecting portion 231 of the connecting member 23 utilizes two second engaging blocks 233 to engage with the second end 212 of the spring 21.

To summarize, the present invention is characterized in that: the first ends 211 of the springs 21 are engaged with at least one first engaging block 223 of each jointing member 22, respectively, the second ends 212 of the springs 21 are engaged with at least one second engaging block 233 of each connecting portion 231 of the connecting member 23, respectively, the jointing members 22 are connected to the backrest 10, and the connecting member 23 is fixed to the office chair 30. When the user sits in the office chair 30 with his back leaning against the backrest 10, since the springs 21 of the connecting unit 20 are flexible, which can enable the backrest 10 to be freely adjusted and moved in response to the movement of the back of the user, producing a buffering effect and providing a comfortable support to the back of the user, so the user will feel comfortable. Moreover, the mounting members 24 for receiving the springs 21 can protect the user from getting pinched by the springs 21, so the present invention is secure.

While we have shown and described various embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention. 

1. A backrest device, comprising: at least one backrest; and at least one connecting unit having two springs, two jointing members and a connecting member, each spring being provided with a first end and a second end arranged in a reverse direction to the first end, the jointing members being fixed to the backrest and the first ends of the springs, respectively, the connecting member being provided with two connecting portions for fixing to the second ends of the springs, respectively.
 2. The backrest device as claimed in claim 1, wherein each jointing member is provided with at least one first engaging block for engaging with the first end of each spring, and each connecting portion of the connecting member is provided with at least one second engaging block for engaging with the second end of each spring.
 3. The backrest device as claimed in claim 1, wherein the backrest device further comprises two mounting members for receiving the springs.
 4. The backrest device as claimed in claim 1, wherein two positioning blocks are provided on a rear surface of the backrest, each positioning block is provided with a threaded sleeve having an inner threaded portion, and each jointing member is defined with a through hole through which a threaded member is threaded in the inner threaded portion of the threaded sleeve of the positioning block, so that the jointing members are fixed to the positioning blocks of the backrest stably.
 5. The backrest device as claimed in claim 1, wherein the backrest device is assembled to a chair whose frame is provided with a built-in nut, the connecting member is defined with a penetrating hole, and a bolt is threaded through the penetrating hole of the connecting member into the built-in nut of the frame to fix the connecting member to the frame.
 6. The backrest device as claimed in claim 3, wherein the mounting members are made of flexible material. 